hi there .. i am new here and i have some questions regarding rac .. i hope this is the right place to ask

i have a couple of questions .

for example if i am going to implement a data of size lets say 100 gb . using export and import utility or whatever after creating rac , so before i create my rac what should i consider ... here are the questions my environment will be SAN for storage are .. my instances will be runing on linux 6)

1) while installing rac do i have to concern about the size of voting disk ?

I've split this into a new thread as it didn't really have anything to do with the thread you added it to.

1) It depends on how you are planning to configure RAC and what type of storage you are using. If you are using NFS, or some cluster file system, then the voting disk is just a file on the shared disk. If you are using ASM, then the voting disk can sit in the disk group, or be placed in a separate disk group.

2) Once again, it depends. They have to be on shared storage, but that can be a cluster file system or on the block devices via ASM. It depends what you choose to do.

3) A LUN is a Logical Unit Number. It is presented to the server and seen and used like a single disk. The LUN can actually be a combination of many disks, with or without mirroring/RAID.

4) The voting disk is tiny (about 256M) so give it about 300M to be on the safe side.

5) Depends. Using vmdk suggests you are using virtual disks. I certainly wouldn't consider that for something real. If I were doing a production RAC installation on VMware, I would use NFS for the storage. It's easy and works well.

6) There is no concept of local disk in RAC. They all have to be shared.

7) If possible, always get the mirroring done by the hardware, not ASM. It performs better and is the recommended option from Oracle's perspective.

Note. I can't give specific answers as there are too many variables to consider. It would be wrong of me to make out I can give you a simple answer as it depends on your infrastructure. I constantly have to compromise what I consider "the right thing to do" because of constraints in the company I work in.

actually this is not what i was concerning about .. i was concerning about the shared disk size ... see when i use vmware or oracle virtual box to install rac i create shared disk .. that shared disk will used for what exactley .

The shared disks are used to hold your database files. In RAC, all the database stuff has to be available to all the nodes, all the time. This is done by using shared storage. If you are doing a virtual installation to play around with RAC you can accomplish this using shared virtual disks. You should not do this for a real installation though! For that you need a proper shared storage solution, like a NAS or SAN.

hi again Mr tim .. right now i will be using SAN and i will be implementing later on some data using export and import or other utility .. and this data will be of size lets say 100 gb .. so what you suggest my shared disk size will be on SAN ... and what to tell the SAN admin to use for the type of disk ( raw or vmdk) ?

Well, based on what I've already said you know the shared disk can't virtual disks, since using shared virtual disks is not appropriate for a "real" installation. You can use a virtual disk for the system disk if you like.

The issue around how to proceed depends on that your virtual environment can cope with. Most people I know avoid trying to mount LUNs directly in virtual environments. Instead, they present the storage as NFS, which is a full functional cluster file system, which means you don't need to use ASM, unless you want to. This in itself presents a problem for some sites, as some sites that use SANs either do not, or can not present storage as NFS shares. This is why I said to you it is impossible for me to give you precise answers to your questions. Many of the answers you seek will depend on your organization and the technology it uses. I can not predict that.

As for size, well, you are a DBA. How much disk do you think it takes to hold your data? If you are using an export, then you know the size of the database you are pulling the data from, so it is not unreasonable to suggest the new database will be the same size.

Hi tim ok i have another question , my client is going to create tow linux serversusing vmware and he is trying to create shared disk ,, so he is trying to create this shared disk using SAN as a storage area ... so is there any documentation for that or any tools ? or what you think !!!

If the SAN can present the disks to the VM and the VM can consume them, then they will be accessed like any other disks from Linux. So for example, if the SAN presents them as iSCSI targets, the Linux VMs can consume them as iSCSI initiators.

Like I said, most people I've spoken to have done RAC on VMware using NFS as the cluster file system because it is far less problematic than other ways.

If you want something definitive, I suggest you or your client contact VMware to ask for their recommendations regarding presenting shared disks to virtual machines on VMware. Just remember that shared virtual disks are not an appropriate solution.

hello tim .. how you doing .. i am trying to import a file to my newly created database .. the file has been exported using expdp (data pump ) any suggest how to import ? as i used to do the same using export and import utility !!!

If you are changing features of the schema you exported, like the schema name, or the tablespace the objects are owned by, you must define the REMAP operations. For example REMAP_DATAFILE, REMAP_SCHEMA and/or REMAP_TABLESPACE.